For the past two decades, low fat, low cholesterol is the mantra of those trying to lose weight, prevent cancer and avoid heart disease. In light of recent studies however, this view is outdated.
Detailed research - particularly that done at Harvard - shows that the total amount of fat in the diet, whether high or low, has no real link with disease. Rather, what really matters is the type of fat in the diet. There are bad fats that increase the risk for certain diseases and good fats that lower the risk. The key is to substitute good fats for bad fats.
Furthermore, low fat diets do not offer an advantage in losing body fat, and in fact are often counterproductive as they cause an increase in muscle loss when compared to high-protein/moderate-fat diets like the Metabolic Diet. The Metabolic Diet and its two main derivatives, the Anabolic Solution and the Radical Diet, use a low-carbohydrate approach to optimize your body’s anabolic and lipolytic hormones to give you the body you want.
How about cholesterol? How bad it is depends on where it is. As it turns out, dietary cholesterol is bad for your heart but it is not the total villain in the picture. The bigger villain is blood cholesterol–the cholesterol circulating in your blood.
High blood cholesterol levels greatly increase the risk for heart disease. But surprisingly, the amount of cholesterol in food is not very strongly linked to cholesterol levels in the blood. What greatly affects blood cholesterol is the mix of fats in the diet.
Dietary Fats
Type of Fat
Main Source
State at Room Temperature
Effect on Cholesterol Levels
Monounsaturated
Olives; olive oil, canola oil, peanut oil; cashews, almonds, peanuts, and most other nuts; avocados
Liquid
Lowers LDL; raises HDL
Polyunsaturated
Corn, soybean, safflower, and cottonseed oils; fish
Liquid
Lowers LDL; raises HDL
Saturated
Whole milk, butter, cheese, and ice cream; red meat; chocolate; coconuts, coconut milk, and coconut oil
Solid
Raises both LDL and HDL
Trans
Most margarines; vegetable shortening; partially hydrogenated vegetable oil; deep-fried chips; many fast foods; most commercial baked goods
Solid or semi-solid
Raises LDL
Too much cholesterol in the blood, though, can lead to problems. In the 1960s and 70s, scientists established a link between high blood cholesterol levels and heart disease. Deposits of cholesterol can build up inside arteries. These deposits, called plaque, can narrow an artery enough to slow or block blood flow. This narrowing process, called atherosclerosis, commonly occurs in arteries that nourish the heart (the coronary arteries).
When one or more sections of heart muscle fail to get the blood, and thus the oxygen and nutrients, they need, the result may be the chest pain known as angina. In addition, plaque can rupture, causing blood clots that may lead to heart attack, stroke, or sudden death. Fortunately, the buildup of cholesterol can be slowed, stopped, and possibly even reversed.
Cholesterol-carrying lipoproteins play a central role the development of atherosclerotic plaque and cardiovascular disease.
The two main types basically work in opposite directions:
Low-density lipoproteins (LDL) carry cholesterol from the liver to the rest of the body. When there is too much LDL cholesterol in the blood, it can be deposited on the walls of the coronary arteries. Because of this, LDL cholesterol is often referred to as the ‘bad’ cholesterol.
High-density lipoproteins (HDL) carry cholesterol from the blood back to the liver, which processes the cholesterol for elimination from the body. HDL makes it less likely that excess cholesterol in the blood will be deposited in the coronary arteries, which is why HDL cholesterol is often referred to as the ‘good’ cholesterol.
When you have your cholesterol checked, the results will indicate your total blood cholesterol level. If you fasted overnight before giving a blood sample, the test results should also include separate counts or your HDL and LDL. In general, the higher your LDL and the lower your HDL, the greater your risk for atherosclerosis and heart disease.
For adults age 20 years or over, the most recent federal guidelines - From the National Cholesterol Education Program - Recommend the following target levels.
Recommended Target Levels:
Total cholesterol less than 200 milligrams per deciliter (mg/dl)
HDL cholesterol levels greater than 40 mg/dl
LDL cholesterol levels less than 100 mg/dl
Dietary Fat, Dietary Cholesterol & Blood Cholesterol
How much cholesterol you’ll have in your blood will depend not so much on total fat you consume butthe type of fat you have had. Cholesterol in the diet contributes too but not as much as people supposed. Egg, for example, had proven to be not as bad as once thought in so far as heart fitness is concerned.
Moderate consumption like one a day does not increase heart disease risk in healthy individuals. While it’s true that egg yolks have a lot of cholesterol and, therefore may slightly affect blood cholesterollevels, eggs also contain nutrients that may help lower the risk for heart disease, including protein, vitamins B12 and D, riboflavin, and folate.
The Villains: Bad Dietary Fats
Saturated Fats. Saturated fats are mainly animal fats. They are found in meat, seafood, whole-milk dairy products (cheese, milk, and ice cream), poultry skin, and egg yolks. Some plant foods are also high in saturated fats, including coconut and coconut oil, palm oil, and palm kernel oil. While saturated fats raise total blood cholesterol levels more than dietary cholesterol does, theytend to raise both the ‘good’ HDL and the ‘bad’ LDL cholesterol.
Trans Fats. Trans fatty acids are fats produced by heating liquid vegetable oils in the presence of hydrogen. This process is known as hydrogenation. The more hydrogenated an oil is, the harder it will be at room temperature. For example, a spreadable tub margarine is less hydrogenated and so has fewer trans fats than a stick margarine.
Most of the trans fats in the American diet are found in commercially prepared baked goods, margarines, snack foods, and processed foods. Commercially prepared fried foods, like French fries and onion rings, also contain a good deal of trans fat.
Trans fats are worse for cholesterol levels than saturated fats because they not only raise LDL (bad) cholesterol, but also lower HDL (good) cholesterol.
The Heroes: Good Dietary Fats
Unsaturated fats are found in products derived from plant sources, such as vegetable oils, nuts, and seeds. There are two main categories: polyunsaturated fats (which are found in high concentrations in sunflower, corn, and soybean oils) and monounsaturated fats (which are found in high concentrations in canola, peanut, and olive oils).
In studies in which polyunsaturated and monounsaturated fats were eaten in place of carbohydrates (in low-carb diets like the Metabolic Diet), these good fats decreased LDL levels and increased HDL levels.
Percentage of Specific Types of Fat in Common Oils and Fats*
Oils
Saturated
Mono-unsaturated
Poly-unsaturated
Trans
Canola
7
58
29
0
Safflower
9
12
74
0
Sunflower
10
20
66
0
Corn
13
24
60
0
Olive
13
72
8
0
Soybean
16
44
37
0
Peanut
17
49
32
0
Palm
50
37
10
0
Coconut
87
6
2
0
Cooking Fats
Shortening
22
29
29
18
Lard
39
44
11
1
Butter
60
26
5
5
Margarine/Spreads
70% Soybean Oil, Stick
18
2
29
23
67% Corn & Soybean Oil Spread, Tub
16
27
44
11
48% Soybean Oil Spread, Tub
17
24
49
8
60% Sunflower, Soybean, and Canola Oil Spread, Tub
18
22
54
5
* Values expressed as percent of total fat; data are from analyses at Harvard School of Public Health Lipid Laboratory and U.S.D.A. publications.
Dietary Fats & Heart Disease - Beyond The ‘30%’ Recommendation
Many health agencies, including the American Dietetic Association, the American Diabetes Association, and the American Heart Association, recommend limiting fat intake to 30% or less of total daily calories as a means of preventing disease. However, there is no good evidence for any particular ‘optimal’ amount of total fat in a healthy diet.
The relation of fat intake to health is one of the areas that Harvard researchers have examined in detail over the last 20 years in two large studies. The Nurses’ Health Study and the Health Professionals Follow-up Study have found no link between the overall percentage of calories from fat and any important health outcome, including cancer, heart disease, and weight gain.
What they have found to be important is the type of fat in the diet. There are clear links between the different types of dietary fats and heart disease. Logically, most of the influence that fat intake has on heart disease is due to its effect on blood cholesterol levels.
Of the bad fats - saturated and trans fats - trans fats are far worse when it comes to heart disease. The Nurses’ Health Study found that replacing only 30 calories (7 grams) of carbohydrates every day with 30 calories (4 grams) of trans fats nearly doubled the risk for heart disease. Saturated fats increased risk as well, but not nearly as much.
For the good fats, there is consistent evidence that high intake of either monounsaturated or polyunsaturated fat lowers the risk for heart disease. In the Nurses’ Health Study, Harvard researchers found that replacing 80 calories of carbohydrates with 80 calories of either polyunsaturated or monounsaturated fats lowered the risk for heart disease by about 30 to 40 percent.
Fish, an important source of the polyunsaturated fat known as omega-3, has received much attention in the past for its potential to lower heart disease risk. And there have been some studies to back this up, although not all have shown consistent benefits. One recent large trial, however, found that by getting 1 gram per day of omega-3 fatty acids over a 3.5 year period, patients who had previous suffered heart attacks could lower their risk of dying from heart disease by 25 percent.
(To get that amount of omega-3 fatty acids would require the equivalent of 1 daily serving of fatty fish, such as mackerel, salmon, sardines, or swordfish.) Although more research is needed, adding fish to the diet may help protect you from heart disease, and it doesn’t have any known risks. The American Heart Association currently recommends that everyone eat at least two servings of fish a week.
Dietary Fat & Obesity
It is a common belief that the more fat you eat, the more body fat you put on, and the more weight you gain. This belief has been bolstered by much of the nutrition advice given to people over the past decade, which has focused on lowering total fat intake while increasing carbohydrate intake. However, current data show that this advice has been misguided. While total fat intake nationwide has dropped over the last decade, rates of obesity have increased steeply.
Most studies show that over the short term, a low-fat diet does result in weight loss. But many diets show such benefits over the short term. On the other hand, low-fat diets appear to offer no substantial advantages over diets with fat levels close to the national average.
Although more research is needed, a prudent recommendation for losing weight or maintain a healthy weight is to be mindful of the amount of food you eat in relation to the amount of calories you burn in a day. Exercising regularly is especially beneficial.
The Bottom Line - Recommendations For Fat Intake
Although the different types of fat have a varied - and admittedly confusing - effect on health and disease, the basic message is simple: limit the bad fats and replace them with good fats. Try to reduce both the trans and saturated fats in your diet as much as possible and replace them with polyunsaturated and monounsaturated fats.
The trickiest of these to attack are the trans fats. That’s because they lurk in many different types of foods and aren’t always included on the food label. But as awareness about trans fats increases, more ‘trans-fat’ free products are becoming available.
This is particularly so in Europe, but many items are also making their appearance in the North America, including trans-fat free margarine (which may also be labeled as ‘non-hydrogenated’margarine). Such labeling of trans fat content has long been up to the food maker’s discretion.
However, a report on trans fats from the Institute of Medicine concluding that there is no safe level of trans fats in the diet has finally prompted the (US) Food and Drug Administration to require that trans fats be listed as part of the Nutrition Facts food label. This decision came after several years of hearings, comments, and negotiations.
Until labels listing trans fats appear, which will probably take a year or more, it will take some detective work to determine if a food contains trans fats. Check the ingredient list for ‘hydrogenated oils.’ The higher up these are listed, the more trans fats the food contains.
Tips For Lowering Trans Fat Intake:
Choose liquid vegetable oils or a soft tub margarine that is contains little or no trans fats.
Reduce intake of commercially prepared baked goods, snack foods, and processed foods, including fast foods.
When foods containing hydrogenated or partially hydrogenated oils can’t be avoided, choose products that list the hydrogenated oils near the end of the ingredient list.
Source:
http://www.hsph.harvard.edu/nutritionsource/fats.html
Diabetes costly among older Americans
April 30, 2008 Uncategorized No Comments
Article from: Online Edition- “The Nation’s Health” – The Official newspaper of the American Public Health Association
Diabetes is harming the nation’s economy as well as its health, according to a University of Michigan study showing that lost productivity among diabetic Americans born between 1931 and 1941 cost the country nearly $133.5 billion by the year 2000.
“Diabetes has a staggering economic impact as well as serious health effects,” said University of Michigan researcher Sandeep Vijan, an assistant professor of internal medicine and lead author of the study, which was funded in part by the Michigan Retirement Research Center at the university’s Institute for Social Research.
About 18.2 million Americans are estimated to have diabetes, and given the aging of the population and the dramatic increase in obesity and sedentary lifestyles even among the young, the prevalence of diabetes is increasing at an epidemic rate. The Centers for Disease Control and Prevention in Atlanta recently estimated that given current trends, one in three people born today will develop the disease.
For the study, published in the December issue of Health Services Research, Vijan and University of Michigan co-authors Rodney Hayward and Kenneth Langa analyzed diabetes-associated mortality, disability, early retirement and work absenteeism among a national household sample of older adults interviewed over an eight-year period. Their analysis was funded primarily by the Social Security Administration, using data from the Health and Retirement Study conducted by the Institute for Social Research.
Funded by the National Institute on Aging, the Health and Retirement Study has conducted interviews every two years since 1992 with a nationally representative sample of 22,000 Americans ages 50 and older to assess major trends in health and economic well-being.
Analyzing the health and work history of study participants who were born between 1931 and 1941, and controlling for other health conditions, the researchers found that diabetes was a significant predictor of lost productivity.
The average person with diabetes lost $2,800 in wages due to early retirement, $630 due to sick days, and $22,100 due to disability, the researchers discovered. When these results were extended to all diabetics born between 1931 and 1941 — 2.3 million people — the economic losses climbed to $58.6 billion. The study also found $60 billion in lost productivity prior to 1992 in the same age group, suggesting a total productivity loss due to diabetes of nearly $120 billion for the eight-year period analyzed.
The analysis excluded people who were already disabled by diabetes at the start of the study. When the lost productivity of this group was added, the economic toll of the disease mounted to $133.5 billion.
As the analysis was limited to Americans born between 1931 and 1941, the total cost of productivity lost as a result of diabetes is much greater, the researchers said.
Still, they point out that there is room for hope, as some of the economic impact of the disease can be attenuated.
“Many diabetes complications are preventable through increased physical activity, improved diet and reduced obesity,” said Langa, an assistant professor of internal medicine and a faculty associate at the Institute for Social Research.
Vijan said that realizing the high economic toll of the disease, employers could offer exercise programs in the workplace, provide and encourage healthy food choices for employees or support disease management programs, all of which can reduce long-term risks of diabetes and its complications.
“Our analyses suggest that such programs are likely to recoup substantial economic gains,” Vijan said. “Indeed, economic analyses of diabetes treatment programs should explicitly consider these individual and societal costs, and policy-makers and others who allocate public health and health care resources should be aware of the potential cost savings of improving diabetes treatment programs.”
Source: University of Michigan Institute for Social Research
Broccoli may help boost the aging immune system
April 30, 2008 Uncategorized No Comments
Article from: Online Edition- “The Nation’s Health” – The Official newspaper of the American Public Health Association
Eat your broccoli! That’s the advice from University of California. Los Angeles, researchers who have found that a chemical in broccoli and other cruciferous vegetables may hold a key to restoring the body’s immunity, which declines as we age.
Published in an online edition of the Journal of Allergy and Clinical Immunology, the study findings show that sulforaphane, a chemical in broccoli, switches on a set of antioxidant genes and enzymes in specific immune cells, which then combat the injurious effects of molecules known as free radicals that can damage cells and lead to disease.
Free radicals are byproducts of normal body processes, such as the metabolic conversion of food into energy, and can also enter the body through small particles present in polluted air. A supercharged form of oxygen, these molecules can cause oxidative tissue damage, leading to disease — for example, triggering the inflammation process that causes clogged arteries. Oxidative damage to body tissues and organs is thought to be one of the major causes of aging.
“The mysteries of aging have always intrigued man,” said Andre Nel, MD, the study’s principal investigator and chief of nanomedicine at the David Geffen School of Medicine at UCLA. “While we have known for some time that free radicals are important in aging, most of the past attention has focused on the mechanisms that produce free radicals rather than addressing the pathways used by the body to suppress their production.”
A dynamic equilibrium exists in the body between the mechanisms that lead to increased free radical production and those antioxidant pathways that help combat free radicals.
“Our study contributes to the growing understanding of the importance of these antioxidant defense pathways that the body uses to fight free radicals,” said Nel, a practicing clinical allergist and immunologist at the Geffen School. “Insight into these processes points to ways in which we may be able to alleviate the effects of aging.”
The delicate balance between pro-oxidant and antioxidant forces in the body could determine the outcome of many disease processes that are associated with aging, including cardiovascular disease, degenerative joint diseases and diabetes, as well as the decline in efficiency of the immune system’s ability to protect against infectious agents.
“As we age, the ability of the immune system to fight disease and infections and protect against cancer wears down as a result of the impact of oxygen radicals on the immune system,” Nel said.
According to the UCLA study, the ability of aged tissues to reinvigorate their antioxidant defense can play an important role in reversing much of the negative impact of free radicals on the immune system. However, until this current study, the extent to which antioxidant defense can impact the aging process in the immune system was not properly understood.
“Our defense against oxidative stress damage may determine at what rate we age, how it will manifest and how to interfere in those processes,” Nel said. “In particular, our study shows that a chemical present in broccoli is capable of stimulating a wide range of antioxidant defense pathways and may be able to interfere with the age-related decline in immune function.”
The UCLA team not only found that the direct administration of sulforaphane in broccoli reversed the decline in cellular immune function in old mice, but they witnessed similar results when they took individual immune cells from old mice, treated those cells with the chemical outside the body and then placed the treated cells back into a recipient animal.
In particular, the scientists discovered that dendritic cells, which introduce infectious agents and foreign substances to the immune system, were particularly effective in restoring immune function in aged animals when treated with sulforaphane.
“We found that treating older mice with sulforaphane increased the immune response to the level of younger mice,” said Hyon-Jeen Kim, first author and research scientist at the Geffen School.
To investigate how the chemical in broccoli increased the immune system’s response, the UCLA group confirmed that sulforaphane interacts with a protein called Nrf2, which serves as a master regulator of the body’s overall antioxidant response and is capable of switching on hundreds of antioxidant and rejuvenating genes and enzymes.
Nel said that the chemistry leading to activation of this gene-regulation pathway could be a platform for drug discovery and vaccine development to boost the decline of immune function in elderly people.
“This is a radical new way of thinking in how to increase the immune function of elderly people to possibly protect against viral infections and cancer,” Nel said. “We may have uncovered a new mechanism by which to boost vaccine responses by using a nutrient chemical to impact oxidant stress pathways in the immune system.”
Kim said that although there is a decline in Nrf2 activity with aging, this pathway remains accessible to chemicals like sulforaphane that are capable of restoring some of the ravages of aging by boosting antioxidant pathways.
The next step is further study to see how these findings would translate to humans.
“Dietary antioxidants have been shown to have important effects on immune function, and with further study, we may be adding broccoli and other cruciferous vegetables to that list,” Nel said.
For now, Nel suggests including these vegetables as part of a healthy diet.
Nel said that these findings offer a window into how the immune system ages.
“We may find that combating free radicals is only part of the answer, Nel said. “It may prove to be a more multifaceted process and interplay between pro- and antioxidant forces.”
Story courtesy University of California, Los Angeles, March 6, 2008. This story does not contain original reporting by The Nation’s Health staff.
ARE YOU GETTING YOUR PROTEIN?
April 28, 2008 Uncategorized No Comments
By: Mauro Di Pasquale
Combining the right foods to get the correct amount and type of protein can be tricky. Mauro Di Pasquale, M.D. gives you tips on what foods you should concentrate on.
In general, proteins of animal origin contain adequate amounts of the essential amino acids and hence they are known as first class proteins. On the other hand, many proteins of vegetable origin are relatively deficient in certain amino acids, notably lysine and the sulphur-containing amino acids.
Mixtures of plant proteins can serve as a complete and well-balanced source of amino acids for meeting human physiological requirements. However the combining of right foods is necessary to obtain the necessary levels of both the essential or indispensable and conditionally indispensable amino acids.
The essential amino acid lysine is consistently at a much lower concentration in all major plant-food protein groups than in animal foods. Since lysine is the limiting amino acid, the addition of limited amounts of lysine to cereal diets improves their protein quality. Studies in Peru and Guatemala have demonstrated that growing children benefited by this addition. In addition, the sulphur-containing amino acids are distinctly lower in legumes and fruits and threonine is lower in cereals compared with amounts found in proteins of animal origin.
Complementary Proteins
There are important differences among and between food products of vegetable and animal origin including the concentrations of proteins and indispensable amino acids that they contain. The concentration of protein and the quality of the protein in some foods of vegetable origin may be too low to make them adequate, sole sources of proteins. In some of the poorer parts of the world, diets are based predominantly on a single plant (e.g. corn) and they frequently lead to malnutrition.
Fortunately, the amino acid deficiencies in a protein can usually be improved by combining it with another so that the mixture of the two proteins will often have a higher food value than either one alone. For example, many cereals are low in lysine, but high in methionine and cysteine. On the other hand, soybeans, Lima beans, and kidney beans are high in lysine but low in methionine and cysteine. When eaten together these types of proteins give a more favorable amino acid profile.
Another example would be the combination of soybean, which is low in sulphur-containing amino acids, with cottonseed, peanut and sesame flour, and cereal grains, which are deficient mainly in lysine. In general oil-seed proteins, in particular, soy protein, can be used effectively in combination with most cereal grains to improve the overall quality of the total protein intake. A combination of soy protein, which is high in lysine, with a cereal that contains a relatively good concentration of sulphur containing amino acids results in a nutritional complementation; the protein quality of the mixture is greater than that for either protein source alone.
Some examples of complementary food proteins include:
Beans and corn (as in tortillas)
Rice and black-eyed peas
Whole wheat or bulgar
Soybeans
Sesame seeds
Soybeans
Peanuts
Brown rice
Bulgar wheat
This kind of supplementation works when the deficient and complementary proteins are ingested together or within a few hours of each other. Various nutritional responses are observed when two dietary proteins are combined. These have been classified by Bressani et al into one of four types.
Type I is an example where no protein complementary effect is achieved. For example, this occurs with combinations of peanut and corn, where each of the protein sources have a common and quantitatively similar lysine deficiency and are both also deficient in other amino acids.
Type II response is observed when combinations are made of two protein sources that have the same limiting amino acid, but in quantitatively different amounts. Corn and cottonseed flour, for example, are both limiting in lysine but cottonseed is relatively less inadequate than is corn.
The third type of response (Type III) demonstrates a true complementary effect because there is a synergistic effect on the overall nutritive value of the protein mixture; the protein quality of the best mix exceeds that of each component alone. This type of response occurs when one of the protein sources has a considerably higher concentration of the most limiting amino acid in the other protein. An example of this response, based on studies in children, is observed when corn and soy flour are mixed so that 60% of the protein intake comes from corn and the remainder from soya protein.
Finally, the Type IV response occurs when both protein sources have a common amino acid deficiency. The protein component giving the highest value is the one containing a higher concentration of the deficient amino acid. Combinations of some textured soy proteins and beef protein follow this type of response.
These nutritional relationships have been determined from rat bioassay studies. However, the more limited results available from human studies with soy and other legumes confirm the applicability of this general concept in human nutrition. This knowledge helps us to understand and evaluate how nutritionally effective combinations of plant protein foods can be achieved.
Even when combinations of plant protein foods are used there is still the concern of timing of ingestion of complementary proteins. Is there a need to ingest different plant proteins at the same time, or within the same meal, to achieve maximum benefit and nutritional value from proteins with different, but complementary, amino acid patterns? This concern may also extend to the question of the need to ingest a significant amount of protein at each meal, or whether it is sufficient to consume protein in variable amounts at different meals and even different days as long as the average daily intake meets or exceeds the recommended or safe protein intakes.
According to FAO/WHO/UNU, estimates of protein requirements refer to metabolic needs that persist over moderate periods of time. However, the body does not store much protein outside of a meager free amino acid pool, and begins certain catabolic processes in the post absorptive phase making the ingestion of regular amounts of protein critical for maximizing the anabolic effects of exercise.
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